Composite wear pad for exhaust nozzle

ABSTRACT

A composite wear pad for being coupled to a slider block of a convergent nozzle of a gas turbine engine includes a high heat capacity composite having a resin and a plurality of carbon fibers bonded together by the resin. The composite wear pad also includes a first rod coupled to the high heat capacity composite at a first axial end of the composite wear pad such that a first end thickness. The composite wear pad also includes a second rod coupled to the high heat capacity composite at a second axial end of the composite wear pad such that the first axial end and the second axial end of the composite wear pad each have an end thickness that is greater than a middle thickness of the composite wear pad.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of, claims priority to and the benefitof, U.S. Ser. No. 14/709,072 filed May 11, 2015 entitled “COMPOSITE WEARPAD FOR EXHAUST NOZZLE,” which is hereby incorporated herein in itsentirety for all purposes.

GOVERNMENT LICENSE RIGHTS

This disclosure was made with government support under FA 8650-09-D-29230021 awarded by The United States Air Force. The government has certainrights in the disclosure.

FIELD

The present disclosure relates generally to convergent nozzles ofaircraft and, more particularly, to wear pads positioned between aslider block and a slider track of a convergent nozzle system.

BACKGROUND

Exhaust from turbine sections of gas turbine engines may includeuncombusted oxygen. Similarly, if the gas turbine engine is a bypassengine, the bypass air also contains oxygen. Some gas turbine enginesmay include an augmentor section capable of providing afterburningcapabilities. In these gas turbine engines, the exhaust from the turbinesection and/or the bypass air may be mixed with additional fuel andcombusted in the augmentor section. This secondary combustion furtherincreases the thrust of the gas turbine engine by increasing velocity ofthe fluid exiting the gas turbine engine. Due to the significantvariance in velocity of the exhaust, some of these gas turbine enginesmay include a variable, or convergent, nozzle capable of changing indimension based on the velocity of the exhaust fluid. This allows thenozzle to have an optimal shape during afterburning and non-afterburningportions of a flight.

SUMMARY

What is described is a composite wear pad for being coupled to a sliderblock of a convergent nozzle of a gas turbine engine. The composite wearpad includes a high heat capacity composite having a resin and aplurality of carbon fibers bonded together by the resin. The compositewear pad also includes a first rod coupled to the high heat capacitycomposite at a first axial end of the composite wear pad such that afirst end thickness. The composite wear pad also includes a second rodcoupled to the high heat capacity composite at a second axial end of thecomposite wear pad such that the first axial end and the second axialend of the composite wear pad each have an end thickness that is greaterthan a middle thickness of the composite wear pad.

Also described is a system. The system includes a slider blockconfigured to slide along a slide track of a convergent nozzle anddefining a first slot having a first outer distance and a first innerdistance that is greater than the first outer distance. The system alsoincludes a composite wear pad having a first axial end having a firstend thickness that is greater than the first outer distance of theslider block such that the composite wear pad resists axial separationin response to the first axial end being positioned within the firstslot.

Also described is a system. The system includes a slider blockconfigured to slide along a slide track of a convergent nozzle anddefining a first slot and a second slot. The system also includes acomposite wear pad that includes a high heat capacity composite having aresin and a plurality of carbon fibers bonded together by the resin. Thecomposite wear pad also includes a first rod coupled to the high heatcapacity composite at a first axial end of the composite wear pad suchthat the first axial end of the composite wear pad can be received bythe first slot. The composite wear pad also includes a second rodcoupled to the high heat capacity composite at a second axial end of thecomposite wear pad such that the second axial end of the composite wearpad can be received by the second slot.

The foregoing features and elements are to be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be understood, however, the following descriptionand drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, is bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the drawing figures, wherein like numeralsdenote like elements.

FIG. 1 is a cross-sectional view of an exemplary gas turbine enginehaving afterburning capabilities, in accordance with variousembodiments;

FIG. 2 illustrates a portion of a convergent nozzle of the gas turbineengine of FIG. 1, in accordance with various embodiments;

FIG. 3 illustrates a convergent flap coupled to a static structure via aslider block and a slider track, in accordance with various embodiments;

FIG. 4 illustrates the slider block of FIG. 3 coupled to a compositewear pad, in accordance with various embodiments;

FIG. 5 illustrates a slider block coupled to a composite wear pad, inaccordance with various embodiments; and

FIG. 6 illustrates a cross-sectional view of the composite wear pad ofFIG. 4, in accordance with various embodiments.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes referenceto the accompanying drawings, which show exemplary embodiments by way ofillustration and their best mode. While these exemplary embodiments aredescribed in sufficient detail to enable those skilled in the art topractice the inventions, it should be understood that other embodimentsmay be realized and that logical, chemical and mechanical changes may bemade without departing from the spirit and scope of the inventions.Thus, the detailed description herein is presented for purposes ofillustration only and not of limitation. For example, the steps recitedin any of the method or process descriptions may be executed in anyorder and are not necessarily limited to the order presented.Furthermore, any reference to singular includes plural embodiments, andany reference to more than one component or step may include a singularembodiment or step. Also, any reference to attached, fixed, connected orthe like may include permanent, removable, temporary, partial, fulland/or any other possible attachment option. Additionally, any referenceto without contact (or similar phrases) may also include reduced contactor minimal contact.

With reference now to FIG. 1, a gas turbine engine 100 is provided. AnA-R-C axis is shown throughout the drawings to illustrate the axial (A),radial (R) and circumferential (C) directions. As used herein, “aft”refers to the direction associated with the tail (e.g., the back end) ofan aircraft, or generally, to the direction of exhaust of the gasturbine engine. As used herein, “forward” refers to the directionassociated with the nose (e.g., the front end) of an aircraft, orgenerally, to the direction of flight or motion. As utilized herein,radially inward refers to the negative R direction and radially outwardrefers to the R direction.

Gas turbine engine 100 may have afterburning capabilities. In thatregard, gas turbine engine 100 may include a nose cone 102, a fansection 104, a compressor section 106, a combustor section 108, aturbine section 110, a tail cone 112, bypass ducts 114, an augmentorsection 132, an augmentor liner 116 and a nozzle section 118. Nose cone102 may improve the aerodynamics of gas turbine engine 100. Nose cone102 may also provide vibration control functions. Fan section 104 mayinclude a plurality of fan blades that rotate about an axis A-A′ of gasturbine engine 100 and propel fluid (such as air) aft. In that regard, aportion of the air is received by compressor section 106 and a portionof the air is received by bypass ducts 114.

The airflow received by compressor section 106 is compressed using aplurality of stages of rotors and stators. The compressed air is thenreceived by combustor section 108 which receives fuel and includes anignition source. The air and fuel are mixed in combustor section 108 andignited, creating a flow of exhaust in the aft direction. The exhaustmay include compounds created during the ignition and some remainingoxygen that did not react during the combustion.

Turbine section 110 may include multiple stages of blades and vanes. Theexhaust created by combustor section 108 is received by turbine section110. In response to receiving the exhaust, the turbine blades rotate,creating torque. The torque created in turbine section 110 may then bemechanically transferred to fan section 104 in order to cause rotationof the plurality of fan blades and/or compressor section 106 in order tocause rotation of the rotors.

Augmentor liner 116 may include a material defining a plurality of holessuch that fluid may pass from one side of augmentor liner 116 to theother side of augmentor liner. In that regard, augmentor section 132 mayreceive the air flowing through bypass ducts 114. Similarly, the exhaustfrom turbine section 110 may be received by augmentor section 132.

The exhaust received by augmentor section 132 may have a velocity. Inthat regard and in various embodiments, the airflow through bypass ducts114 and the exhaust from turbine section 110 may flow through augmentorsection 132 and provide thrust. Augmentor section 132 may include anignition source and be capable of receiving additional fuel. In responseto augmentor section 132 receiving fuel and initiating combustion, theoxygen from the exhaust and the air received via bypass ducts 114 maymix with the fuel and be combusted. This creates a second exhaust havinga higher velocity than the velocity of the received exhaust, thusgenerating more thrust than when combustion is not occurring inaugmentor section 132.

Nozzle section 118 may receive air and/or exhaust from augmentor section132 and may further increase the velocity of the air and/or exhaust.Nozzle section 118 may be a convergent nozzle such that it includes aconvergent section 120 and a divergent section 122 that meet at throat124.

The velocity of exhaust flowing through nozzle section 118 may varybased on whether combustion is occurring in augmentor section 132 or notsuch that the velocity may be greater if combustion is occurring inaugmentor section 132. Accordingly and with reference to FIGS. 1 and 2,a diameter 130 of nozzle section 118 may be selectively altered bychanging position of a convergent flap 202 relative to a staticstructure 200. The diameter 130 may be selectively altered based on thevelocity of exhaust flowing through nozzle section 118. This furtheralters an angle 126 between convergent section 120 and throat 124 aswell as an angle 128 between divergent section 122 and throat 124.Nozzle section 118 may thus be changed to provide optimal accelerationof the exhaust based on the velocity of the exhaust.

Static structure 200 may define and/or include a slider track 206. Aslider block 204 may be coupled to convergent flap 202 and slider track206. Slider block 204 may be capable of being received by and slidealong slider track 206 and be capable of changing position axially andradially relative to static structure 200. In response to slider block204 changing position, diameter 130 of throat 124 is increased ordecreased. In response to slider block 204 moving aft relative to staticstructure 200 from a forward position, a forward end of inner surface210 of divergent section 122 may move radially inward, increasingdiameter 130. Similarly, in response to slider block 204 moving forwardrelative to static structure 200 from an aft positon, the forward end ofinner surface 210 of divergent section 122 may move radially outward,reducing diameter 130.

With reference now to FIG. 3, a composite wear pad 300 may be coupled toslider block 204 and positioned between an outer surface 304 of sliderblock 204 and an outer surface 302 of slider track 206. Similarly, asecond composite wear pad 306 may be coupled to slider block 204 andpositioned between an outer surface 308 of slider block 204 and an innersurface 310 of slider block 204.

As mentioned above and in various situations, slider block 204 maychange position relative to slider track 206. During this motion,friction may occur between outer surface 304 of slider block 204 andouter surface 302 of slider track 206. In a similar manner, convergentflap 202 may change position relative to slider block 204, creatingfriction between outer surface 308 of convergent flap 202 and innersurface 310 of slider block 204. In that regard, composite wear pad 300and second composite wear pad 306 may be positioned at these frictionpoints and may resist the friction.

With reference now to FIGS. 3 and 6, composite wear pad 300 may includea high heat capacity composite 301 having plurality of carbon fibers 600bonded using a resin at 602. In various embodiments, plurality of carbonfibers 600 may have some fibers aligned in a first direction and otherfibers aligned in a second direction, creating a woven pattern fromplurality of carbon fibers 600. In various embodiments, plurality ofcarbon fibers may all be aligned in the axial direction such that alongitudinal axis of each fiber is parallel to slider track 206 in theaxial direction. In various embodiments, resin 602 may include a hightemperature thermosetting polyimide resin such as AFR-PE-4™, availablefrom Maverick Corporation of 11359 Grooms Road, Blue Ash, Ohio.Plurality of carbon fibers 600 and resin 602 may be resistant to heat.In various embodiments, the plurality of carbon fibers 600 and resin 602may be resistant to temperatures up to 250 degrees Celsius (250° C.,482° F.), up to 300° C. (572° F.) or up to 350° C. (662° F.). Secondcomposite wear pad 306 may also include a high heat capacity compositehaving a plurality of carbon fibers 600 bonded using a resin. In variousembodiments, the resin may include a high temperature thermosettingpolyimide resin and the plurality of carbon fibers and the resin may beresistant to heat.

Because slider block 204 changes position relative to slider track 206,friction can occur between the two. Thus, composite wear pad 300 may besubjected to friction between the two. The carbon used in plurality ofcarbon fibers 600 includes friction-based wear resistance, thus,composite wear pad 300 resists wear during use. This results in a longerlifespan of composite wear pad 300 than if it comprised differentmaterials having less wear-resistant properties.

Temperatures near slider block 204 can be relatively high, as hotexhaust flows in close proximity to slider block 204. Because of this,it is undesirable to use grease between slider block 204 and slidertrack 206. However, the properties of the carbon of plurality of carbonfibers 600 provide a low-friction interface, reducing the need forlubrication. This property reduces an amount of friction between outersurface 304 of slider block 204 and outer surface 302 of slider track206. This also provides advantages such as reducing or eliminating arequirement for changing grease in this location. Another benefit is thereduction of debris, as grease may attract debris.

With reference now to FIG. 4, slider block 204 may define a first slot402 and a second slot 403. In various embodiments, high heat capacitycomposite 301 may circumferentially surround a first rod 404 on a firstside of composite wear pad 300 and circumferentially surround a secondrod 405 on a second side of composite wear pad 300. In variousembodiments, first rod 404 and second rod 405 may have a cylindricalshape such that high heat capacity composite 301 may enclose the curvedsurface of cylindrical first rod 404 and cylindrical second rod 405. Invarious embodiments, first rod 404 and second rod 405 may include ametal such as steel, steel alloy, titanium or the like.

During manufacture and after first rod 404 and second rod 405 arecircumferentially surrounded by composite wear pad 300, high heatcapacity composite 301, first rod 404 and second rod 405 may be co-curedtogether, for example, using an Autoclave. In various embodiments, thecuring may be performed in a high pressure and high temperatureenvironment. In various embodiments, high heat capacity composite 301,first rod 404, second rod 405 and slider block 204 may be curedtogether. Because first rod 404 and second rod 405 are cured togetherand used in a relatively high-temperature environment, first rod 404 andsecond rod 405 may include titanium, as a coefficient of thermalexpansion of titanium closely matches that of the material of compositewear pad 300.

High heat capacity composite 301 may have a middle thickness 456 andfirst axial end 460 and second axial end 463 of composite wear pad 300may have an end thickness 452. End thickness 452 may be measured as thelargest thickness of the portion of composite wear pad 300 includingfirst rod 404 or second rod 405 and may be greater than middle thickness456. First slot 402 and second slot 403 may have an inner distance 453and an outer distance 454. Inner distance 453 may be greater than outerdistance 454 and positioned axially aft relative to a first axial end460 of composite wear pad 300. Inner distance 453 may be the same as orslightly greater than end thickness 452 of composite wear pad 300 (i.e.,within five percent (5%) or within 10% of end thickness 452). Similarly,outer distance 454 may be the same as or slightly greater than middlethickness 456 (i.e., within 5% or within 10% of middle thickness 456).

Outer distance 454 may be positioned on first axial end 460 above anaxial arm 462 of slider block 204. In that regard, first axial end 460of composite wear pad 300 may be circumferentially aligned with firstslot 402 and force may be applied to composite wear pad 300 in thecircumferential direction, causing first axial end 460 to slide intofirst slot 402. Because end thickness 452 is greater than outer distance454, first axial end 460 may resist separation from slider block 204 inthe axial direction. Second axial end 463 of composite wear pad 300 mayresist axial separation in the same manner.

Because first rod 404 and second rod 405 are cured with high heatcapacity composite 301, the rods resist separation from high heatcapacity composite 301. With reference to FIGS. 3 and 4 and based on theshape of annular cavity of first slot 402 and second slot 403, inresponse to the portions of composite wear pad 300 containing first rod404 and second rod 405 being inserted into first slot 402 and secondslot 403, composite wear pad 300 will resist separation from sliderblock 204. This is particularly true in response to axial movement ofslider block 204 relative to static structure 200. As an additionalbenefit of coupling composite wear pad 300 to slider block 204 in thismanner and returning reference to FIG. 4, in response to replacement ofcomposite wear pad 300 being desired, a new composite wear pad may becoupled to slider block 204 without replacing slider block 204. This isachieved by applying a circumferential force to composite wear pad 300such that first axial end 460 and second axial end 463 of composite wearpad 300 slide out from first slot 402 and second slot 403.

In various embodiments and with reference to FIG. 5, a slider block 510may define a first triangular slot 500 and a second triangular slot 501,each defining a cavity having a triangular prism shape. Similarly, acomposite wear pad 520 may include a high heat capacity composite 505having a first end 512 coupled to a first triangular rod 502 and asecond end 518 coupled to a second triangular rod 503. First end 512 mayinclude a first flap 514 positioned on a base of first triangular rod502 and another flap 516 positioned on another base of first triangularrod 502. High heat capacity composite 505, first triangular rod 502 andsecond triangular rod 503 may be co-cured together in order to couplecomposite wear pad 520 to first triangular rod 502 and second triangularrod 503, such that high heat capacity composite 505, first triangularrod 502 and second triangular rod 503 resist separation. Due to thetriangular cavity of first triangular slot 500 and second triangularslot 501, composite wear pad 520 will resist separation from sliderblock 510.

In various embodiments and with reference to FIGS. 3 and 4, secondcomposite wear pad 306 may include a high heat capacity compositesimilar to high heat capacity composite 301 and rods similar to firstrod 404 and second rod 405 and slider block 204 may include slotssimilar to first slot 402 and second slot 403. In that regard, secondcomposite wear pad 306 may be coupled to slider block 204 in a similarmanner as composite wear pad 300 is coupled to slider block 204.

In various embodiments, the slots of the slider block may have any shapeso long as an inner distance of the slot is larger than an outerdistance of the slot. A composite wear pad may include a rod having ashape similar to the slots such that in response to a high heat capacitycomposite being coupled to the rod, the combination of the high heatcapacity composite and the rod form a shape that substantially fills avolume defined by the slots (i.e., the volume of the high heat capacitycomposite coupled to the rod is within 5% or within 10% of the volumedefined by a slot) and may not separate from the slots in response toaxial movement of the slider block relative to a static structure, dueto the end thickness of the rods being larger than the outer distance ofthe slots.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the inventions. The scope of the invention is accordingly tobe limited by nothing other than the appended claims, in which referenceto an element in the singular is not intended to mean “one and only one”unless explicitly so stated, but rather “one or more.” Moreover, where aphrase similar to “at least one of A, B, or C” is used in the claims, itis intended that the phrase be interpreted to mean that A alone may bepresent in an embodiment, B alone may be present in an embodiment, Calone may be present in an embodiment, or that any combination of theelements A, B and C may be present in a single embodiment; for example,A and B, A and C, B and C, or A and B and C. Different cross-hatching isused throughout the figures to denote different parts but notnecessarily to denote the same or different materials.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f), unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

The invention claimed is:
 1. A slider block of a convergent nozzle of agas turbine engine, the slider block comprising: a body comprising afirst end and a second end opposite the first end, wherein a first axialarm extends from the first end and a second axial arm extends from thesecond end, wherein the first end defines a first slot above the firstaxial arm and the second end defines a second slot above the secondaxial arm; and a wear pad comprising: a high heat capacity compositehaving a resin and a plurality of carbon fibers bonded together by theresin; a first rod coupled to the high heat capacity composite at afirst axial end of the wear pad; and a second rod coupled to the highheat capacity composite at a second axial end of the wear pad; whereinthe first axial end of the wear pad wraps around the first axial arm ofthe body and the first rod is retained within the first slot; whereinthe second axial end of the wear pad wraps around the second axial armof the body and the second rod is retained within the second slot; andwherein the wear pad is configured such that the first axial end and thesecond axial end of the wear pad each have an end thickness that isgreater than a middle thickness of the wear pad.
 2. The slider block ofclaim 1, wherein the first rod and the second rod are made of a metalmaterial.
 3. The slider block of claim 2, wherein the metal materialcomprises at least one of steel and titanium.
 4. The slider block ofclaim 1, wherein the first rod and the second rod are co-cured with thewear pad.
 5. The slider block of claim 1, wherein the first rod, thesecond rod, and the high heat capacity composite are co-cured with theslider block.
 6. A slider block of a convergent nozzle of a gas turbineengine, the slider block comprising: a body comprising a first end and asecond end opposite the first end, wherein a first axial arm extendsfrom the first end and a second axial arm extends from the second end,wherein the first end defines a first slot above the first axial arm andthe second end defines a second slot above the second axial arm; and awear pad comprising: a high heat capacity composite having a resin and aplurality of carbon fibers bonded together by the resin; a first rodcoupled to the high heat capacity composite at a first axial end of thewear pad; and a second rod coupled to the high heat capacity compositeat a second axial end of the wear pad; wherein the first axial end ofthe wear pad wraps around the first axial arm of the body and the firstrod is retained within the first slot; wherein the second axial end ofthe wear pad wraps around the second axial arm of the body and thesecond rod is retained within the second slot; and wherein the first rodand the second rod are co-cured with the wear pad.
 7. A slider block ofa convergent nozzle of a gas turbine engine, the slider blockcomprising: a body comprising a first end and a second end opposite thefirst end, wherein a first axial arm extends from the first end and asecond axial arm extends from the second end, wherein the first enddefines a first slot above the first axial arm and the second enddefines a second slot above the second axial arm; and a wear padcomprising: a high heat capacity composite having a resin and aplurality of carbon fibers bonded together by the resin; a first rodcoupled to the high heat capacity composite at a first axial end of thewear pad; and a second rod coupled to the high heat capacity compositeat a second axial end of the wear pad; wherein the first axial end ofthe wear pad wraps around the first axial arm of the body and the firstrod is retained within the first slot; wherein the second axial end ofthe wear pad wraps around the second axial arm of the body and thesecond rod is retained within the second slot; and wherein the firstrod, the second rod, and the high heat capacity composite are co-curedwith the slider block.